nat_api_stun.c File Reference

This code provides some support for doing STUN transactions. More...

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_resolver_service.h"
#include "gnunet_nat_service.h"
#include "nat_stun.h"

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Data Structures
struct	GNUNET_NAT_STUN_Handle
	Handle to a request given to the resolver. More...

Macros
#define	LOG(kind, ...)   GNUNET_log_from (kind, "stun", __VA_ARGS__)
#define	TIMEOUT   GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)

Functions
static int	encode_message (enum StunClasses msg_class, enum StunMethods method)
	Encode a class and method to a compatible STUN format.
static void	generate_request_id (struct stun_header *req)
	Fill the stun_header with a random request_id.
static void	stun_dns_callback (void *cls, const struct sockaddr *addr, socklen_t addrlen)
	Try to establish a connection given the specified address.
struct GNUNET_NAT_STUN_Handle *	GNUNET_NAT_stun_make_request (const char *server, uint16_t port, struct GNUNET_NETWORK_Handle *sock, GNUNET_NAT_TestCallback cb, void *cb_cls)
	Make Generic STUN request.
void	GNUNET_NAT_stun_make_request_cancel (struct GNUNET_NAT_STUN_Handle *rh)
	Cancel active STUN request.

Detailed Description

This code provides some support for doing STUN transactions.

We send simplest possible packet ia REQUEST with BIND to a STUN server.

All STUN packets start with a simple header made of a type, length (excluding the header) and a 16-byte random transaction id. Following the header we may have zero or more attributes, each structured as a type, length and a value (whose format depends on the type, but often contains addresses). Of course all fields are in network format.

This code was based on ministun.c.

Functions for STUN functionality

Author

Bruno Souza Cabral

Definition in file nat_api_stun.c.

Macro Definition Documentation

LOG

#define LOG	(		kind,
			...
	)		GNUNET_log_from (kind, "stun", __VA_ARGS__)

Definition at line 46 of file nat_api_stun.c.

TIMEOUT

#define TIMEOUT   GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)

Definition at line 48 of file nat_api_stun.c.

Function Documentation

encode_message()

static int encode_message ( enum StunClasses  msg_class, enum StunMethods  method  )

static

Encode a class and method to a compatible STUN format.

Parameters

msg_class	class to be converted
method	method to be converted

Returns

message in a STUN compatible format

Definition at line 103 of file nat_api_stun.c.

{
  return ((msg_class & 1) << 4) | ((msg_class & 2) << 7)
         | (method & 0x000f) | ((method & 0x0070) << 1) | ((method & 0x0f800)
                                                           << 2);
}

Referenced by stun_dns_callback().

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generate_request_id()

static void generate_request_id ( struct stun_header *  req )

static

Fill the stun_header with a random request_id.

Parameters

req	stun header to be filled

Definition at line 118 of file nat_api_stun.c.

{
  req->magic = htonl (STUN_MAGIC_COOKIE);
  for (unsigned int x = 0; x < 3; x++)
    req->id.id[x] = GNUNET_CRYPTO_random_u32 (UINT32_MAX);
}

References GNUNET_CRYPTO_random_u32(), stun_trans_id::id, stun_header::id, stun_header::magic, and STUN_MAGIC_COOKIE.

Referenced by stun_dns_callback().

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stun_dns_callback()

static void stun_dns_callback ( void *  cls, const struct sockaddr *  addr, socklen_t  addrlen  )

static

Try to establish a connection given the specified address.

Parameters

cls	our struct GNUNET_NAT_STUN_Handle *
addr	address to try, NULL for "last call"
addrlen	length of addr

Definition at line 134 of file nat_api_stun.c.

{
  struct GNUNET_NAT_STUN_Handle *rh = cls;
  struct stun_header req;
  struct sockaddr_in server;
 
  if (NULL == addr)
  {
    rh->dns_active = NULL;
    if (GNUNET_NO == rh->dns_success)
    {
      LOG (GNUNET_ERROR_TYPE_INFO,
           "Error resolving host %s\n",
           rh->stun_server);
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_NOT_ONLINE);
    }
    else if (GNUNET_SYSERR == rh->dns_success)
    {
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_INTERNAL_NETWORK_ERROR);
    }
    else
    {
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_SUCCESS);
    }
    GNUNET_NAT_stun_make_request_cancel (rh);
    return;
  }
 
  rh->dns_success = GNUNET_YES;
  memset (&server, 0, sizeof(server));
  server.sin_family = AF_INET;
  server.sin_addr = ((struct sockaddr_in *) addr)->sin_addr;
  server.sin_port = htons (rh->stun_port);
#if HAVE_SOCKADDR_IN_SIN_LEN
  server.sin_len = (u_char) sizeof(struct sockaddr_in);
#endif
 
  /* Craft the simplest possible STUN packet. A request binding */
  generate_request_id (&req);
  req.msglen = htons (0);
  req.msgtype = htons (encode_message (STUN_REQUEST,
                                       STUN_BINDING));
 
  /* Send the packet */
  if (-1 ==
      GNUNET_NETWORK_socket_sendto (rh->sock,
                                    &req,
                                    sizeof(req),
                                    (const struct sockaddr *) &server,
                                    sizeof(server)))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
                         "sendto");
    rh->dns_success = GNUNET_SYSERR;
    return;
  }
}

References GNUNET_NAT_STUN_Handle::cb, GNUNET_NAT_STUN_Handle::cb_cls, GNUNET_NAT_STUN_Handle::dns_active, GNUNET_NAT_STUN_Handle::dns_success, encode_message(), generate_request_id(), GNUNET_ERROR_TYPE_ERROR, GNUNET_ERROR_TYPE_INFO, GNUNET_log_strerror, GNUNET_NAT_ERROR_INTERNAL_NETWORK_ERROR, GNUNET_NAT_ERROR_NOT_ONLINE, GNUNET_NAT_ERROR_SUCCESS, GNUNET_NAT_stun_make_request_cancel(), GNUNET_NETWORK_socket_sendto(), GNUNET_NO, GNUNET_SYSERR, GNUNET_YES, LOG, stun_header::msglen, stun_header::msgtype, GNUNET_NAT_STUN_Handle::sock, STUN_BINDING, GNUNET_NAT_STUN_Handle::stun_port, STUN_REQUEST, and GNUNET_NAT_STUN_Handle::stun_server.

Referenced by GNUNET_NAT_stun_make_request().

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